Balloon loaded dissecting instruments

ABSTRACT

Balloon loaded dissection devices with elongate balloon and a pushing member are disclosed for creating a tunnel alongside an elongate vessel in the body. The devices may utilize an elongate balloon of any suitable length which may be formed of an elastic or non-elastic material. The balloon may be of double walled construction and may be provided with a central lumen which may receive a guide rod, scope or other surgical instrument. The device may have a support tube secured to the inner wall of the balloon to provide columnar support for the apparatus. The support tube receives the guide rod, scope or other surgical instrument and may have a stop member to translate pushing force applied to the guide rod or scope to pushing force on the apparatus. By using the guide rod or scope as a pushing member the apparatus may be advanced alongside the vessel it is desired to dissect free from attached tissue. A balloon cover which may be elastic or resilient is provided to surround the balloon and facilitate compression of the balloon after it is deflated.

FIELD OF THE INVENTION

This invention relates to methods and devices for endoscopic vascularsurgery, in particular to methods and devices for dissecting tissue tocreate a working space over a blood vessel.

BACKGROUND OF THE INVENTION

Numerous surgical procedures have been developed to replace arteriesthat have become blocked by disease. The aortocoronary bypass surgery isperhaps the most important of these bypass operations. The coronaryarteries supply blood to the heart. As a result of aging and disease,coronary arteries may become blocked by plaque deposits, stenosis, orcholesterol. In some instances, these blockages can be treated withatherectomy, angioplasty or stent placement, and coronary bypass surgeryis not required. Coronary bypass surgery is required when these othermethods of treatment cannot be used or have failed to clear the blockedartery. In coronary bypass surgery, a vein is harvested from elsewherein the body and grafted into place between the aorta and the coronaryartery below the point of blockage. An illustration of this surgery isshown in FIG. 1, which shows the heart 1 and the right anterior coronaryartery 2 and the left anterior coronary artery 3 which supply blood tothe heart. The right anterior coronary artery 2 is blocked in itsproximal segment at 2a, as shown. This blockage has been bypassed bygrafting a segment of vein 4 between the aorta 5 and the distal segment2b of the right anterior coronary artery 2. Similarly, the left anteriorcoronary artery 3 may be blocked, and may require bypass with a lengthof vein 4a between the aorta and the distal segment 3b of the leftanterior artery. The operation requires access to the heart, which meansthat the chest cavity must be opened completely.

The coronary bypass surgery requires a length of vein or artery for thegraft. It is preferred to use a vein taken from the patient undergoingthe bypass surgery. The patient is a ready source of suitable veins thatwill not be rejected by the body after transplantation and grafting ontothe aorta and coronary artery. The saphenous vein in the leg is the bestsubstitute for small arteries such as the coronary arteries, and it isthe preferred vein for use in coronary bypass surgery. This is becausethe saphenous vein is typically 3 to 5 mm in diameter, about the samesize as the coronary arteries. Also, the venous system of the legs issufficiently redundant so that after removal of the saphenous vein otherveins that remain in the leg are adequate to provide adequate returnblood flow. The cephalic vein in the arm is an alternative that issometimes used.

A typical operation previously required to harvest the saphenous vein isillustrated in FIG. 2. The surgeon cuts into the leg to allow access tothe saphenous vein and cuts the vein from the leg. To expose thesaphenous vein 6, the surgeon makes a series of incisions from the groin7 to the knee 8 or the ankle 9, leaving a one or more skin bridges 10along the line of the incisions. Some surgeons make one continuousincision from the groin to the knee or ankle. Handling of the vein mustbe kept to a minimum, but the vein must be removed from connectivetissue that requires some force to remove. After exposing the vein, thesurgeon grasps it with his fingers while stripping off the surroundingtissues with dissecting scissors or other scraping instruments. Thesurgeon uses his fingers and blunt dissection tools to pull and lift (ormobilize) the vein from the surrounding tissue. The vein is mobilized orpulled as far as possible through each incision. To reach under the skinbridges, the surgeon lifts the skin with retractors and digs the veinfree. While stripping the vein, the surgeon will encounter the varioustributary veins that feed into the saphenous vein. These tributariesmust be ligated and divided. To divide and ligate tributaries that lieunder the skin bridges, the surgeon may need to cut one end of thesaphenous vein and pull it under the skin bridge to gently pull the veinout from under the skin bridge until the tributary is sufficientlyexposed so that it may be ligated and divided. When the vein has beencompletely mobilized, the surgeon cuts the proximal and distal ends ofthe vein and removes the vein from the leg. After removal, the vein isprepared for implantation into the graft site, and the long incisionsmade in the leg are stitched closed.

The procedure described above can be used to harvest veins for a femoralpopliteal bypass, in which an occluded femoral artery is bypassed fromabove the occlusion to the popliteal artery near the level of the knee.The procedure can also be used to harvest veins for therevascularization of the superior mesenteric artery which supplies bloodto the abdominal cavity and intestines. In this case, the harvested veinis inserted between the aorta to the distal and patent (unblocked)section of the mesenteric artery. For bypass grafts of the lowerpopliteal branches in the calf, the procedure can be used to harvest theumbilical vein. The harvested vein can also be used for a vein loop inthe arm (for dialysis) between the cephalic vein and brachial artery.

As can be seen from the description of the harvesting operation, theharvesting operation is very traumatic in its own right. In the case ofcoronary artery bypass, this operation is carried out immediately beforethe open chest operation required to graft the harvested vein into thecoronary arteries. The vein harvesting operation is often the mosttroublesome part of the operation. The long incisions created in the legcan be slow to heal and very painful. Complications resulting from thevein harvesting operation can also hinder the patient's recovery fromthe entire operation.

The method of vein harvesting presented herein is accomplished withlaparoscopic procedures. This allows the veins to be harvested in anoperation that requires only a few small incisions. Endoscopic surgicaltechniques for operations such as gall bladder removal and hernia repairare now common. The surgeon performing the operation makes a few smallincisions and inserts long tools, including forceps, scissors, andstaplers, into the incision and deep into the body. Viewing the toolsthrough a laparoscope or a video display from the laparoscope, thesurgeon can perform a wide variety or maneuvers, including cutting andsuturing operations, necessary for a wide variety of surgical proceduresand operations.

Minimally invasive procedures for vein removal have been proposed.Knighton, Endoscope and Method for Vein Removal, U.S. Pat. No. 5,373,840shows a method of cutting the saphenous vein at one end, and graspingthe vein with graspers or forceps, then sliding a ring over the veinwhile holding it. Knighton uses a dissecting tool with an annularcutting ring, and requires that the saphenous vein be overrun orprogressively surrounded with the dissecting tool and the endoscope, sothat after the endoscope has been inserted as far as it will go, theentire dissected portion of the vein has been pulled into the lumen ofthe endoscope. As shown in FIGS. 1 and 10 of Knighton, the methodrequires deployment of forceps inside the annular dissection loop, andit requires deployment of the loop and graspers inside the endoscopelumen. The blood vessel must be cut and grasped by the forceps before itcan be dissected by the dissecting ring.

The method of vein harvesting disclosed herein uses a balloon to assistin dissecting the harvested vein. An uninflated tubular balloon wrappedaround a guide rod or endoscope and covered with an easily removableballoon cover is inserted into one of the small incisions and pushedalong the vein to create a small tunnel over the vein. When the balloonis in place over the vein, the balloon cover may be left in place or itmay be removed and the balloon is inflated to enlarge the tunnel andcreate a work space for insertion of endoscopic instruments. The guiderod or endoscope may be removed to allow other endoscopic instruments tobe passed into the tunnel through the balloon.

SUMMARY OF THE INVENTION

The methods and devices disclosed herein allow surgeons to harvest veinswithout making long incisions as has previously been required.

In a preferred embodiment, a blunt loaded balloon dissector has anelongate balloon of any suitable length which may be formed of anelastic or non-elastic material. The balloon may be of double walledconstruction and may be provided with a central lumen which may receivea guide rod, scope or other surgical instrument. The device may have asupport tube secured to the inner wall of the balloon to providecolumnar support for the apparatus. The support tube receives the guiderod, scope or other surgical instrument and may have a stop member totranslate pushing force applied to the guide rod or scope to pushingforce on the apparatus. By using the guide rod or scope as a pushingmember the apparatus may be advanced alongside the vessel it is desiredto dissect free from attached tissue. A balloon cover which may beelastic or resilient is provided to surround the balloon and facilitatecompression of the balloon after it is deflated.

In another embodiment of the invention, another pushable balloondissection device is provided which also may utilize an elongateballoon. The balloon in this embodiment is elongate and may have acentral lumen to receive a scope or other laparoscopic instrument. Theapparatus has a guide tube which receives a guide rod with a slendermetal rod and enlarged tip. The guide rod is utilized as a pushingmember. A balloon cover may also be provided in this embodiment.

The present devices permit minimally invasive procedures which requirejust two small incisions, one at either end of the saphenous vein, to beperformed. The procedure is accomplished with laparoscopic instrumentsunder the guidance of a laparoscope. The surgeon makes one smallincision at each end of the saphenous vein. After making the incisions,the surgeon inserts a tunneling instrument or blunt dissector whichcarries a long balloon into one incision and advances or pushes alongthe saphenous vein to make a small tunnel along the saphenous vein. Thesurgeon then inflates the long balloon to enlarge the tunnel. When thetunnel is enlarged to an appropriate size, the surgeon removes theballoon and seals the tunnel at both ends. The surgeon then injectscarbon dioxide into the tunnel at sufficient pressure (typically 5-15 mmHg) to inflate the tunnel and create room for laparoscopic instruments.The surgeon then inserts a laparoscope through the seal to provide aview of the procedure, and inserts a laparoscopic vein harvesting devicedescribed in co-pending U.S. application Ser. No. 08/444,424 entitled,"Methods and Devices for Blood Vessel Harvesting," the disclosure ofwhich is hereby incorporated by reference in its entirety, to dissectthe connective tissue from the vein, identify side branches, and removethe vein from the leg. After the vein is loosened or dissected free fromits channel in the leg, the surgeon can cut the proximal and distal endsof the vein and easily pull the vein from the leg. The small skinincisions are stitched so that they may heal. The small incisions healmuch more readily, with fewer complications and far less pain, than theopen procedures now in use.

DETAILED DESCRIPTION OF DRAWINGS

FIG. 1 is a front view of the heart showing a vein grafted from theaorta to the fight anterior coronary artery, bypassing the proximalsegment of the right anterior coronary artery.

FIG. 2 is a view of the leg showing the incisions necessary forharvesting the saphenous vein using a traditional open procedure.

FIGS. 3, 3a and 3b are views of the leg showing the incisions necessaryfor harvesting the saphenous vein using the methods presented herein.

FIG. 4 shows a balloon dissector according to the invention uninflatedand ready for insertion.

FIG. 5 shows a balloon dissector according to the invention in itsinflated state.

FIG. 6 is a cross-section of an alternate embodiment of a balloondissector in its uninflated state.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 4 shows an embodiment of a balloon loaded blunt dissector 15 in itsuninflated state with a balloon 16 packed inside the device. The balloon16 is a nonelastic balloon or bladder and is cylindrical or tubular witha central lumen 17. The balloon 16 has two walls 18 and 19 and may bedescribed as a double walled balloon tube. The balloon 16 may be made ofpolyethylene, polyurethane, polyamide and other nonelastic materials aswell as latex and other elastic materials. The balloon 16 may be anysuitable length, for example 12 to 24 inches long, to provide a tunnelof convenient length when harvesting the saphenous vein. The balloon 16may be any convenient diameter or width, for example 2 to 3 inches, toallow laparoscopic instruments to fit and operate conveniently withinthe tunnel created by the balloon 16. The balloon tube 16 may have anysuitable cross-sectional shape.

A guide rod 20 with a blunt or rounded tip 21 is disposed in the centrallumen 17 of the double walled balloon tube 16. The guide rod 20 is usedas a pushing member to push the balloon 16 through body tissue. Asupport tube 22 may be provided to give some columnar support to thedevice and provide a stop member or coupling member to translate pushingforce applied to the guide rod 20 to pushing action on the balloon tube16. The support tube 22 may have an overhanging lip 23 which obstructspassage of the guide rod 20 or endoscope 29 (if provided).Alternatively, the guide rod 20 or endoscope 29 can be fitted with astop collar 30 to engage the support tube 22 (as shown in FIG. 5). Thesupport tube 22 may have a square tip 25 as in FIG. 4 or a rounded tip26 as shown in FIG. 5. The guide rod 20 and support tube 22 are used topush the balloon 16 along the saphenous vein or other desired pathwaybetween tissue layers. Use of the support tube 22 permits the guide rod20 or endoscope 29, if utilized as the pushing member, to be removablyreceived by the apparatus 15. This allows the apparatus 15 to use fairlyexpensive and nondisposable devices such as the endoscope as the pushingmember. If visualization is not needed or desired, the balloon 16 may besealed to a disposable pushing member and may be coupled to the pushingmember with adhesives, heat sealing or integral construction or anyother coupling means.

A balloon cover 27 surrounds the balloon tube 16 and provides aprotective sheath during placement of the balloon loaded dissector 15.The balloon cover 27 may be a thin sheath of polyethylene or otherplastic film, or it may be a more rigid tube of PVC, PTFE, PETG,polyethylene or other plastic. The balloon cover 27 may be elastic orresilient so that it serves to compress the balloon 16, so that theballoon 16 quickly and automatically collapses upon deflation. Theballoon cover 16 may be made resilient by choosing a resilient materialsuch as a thin sheet of polyethylene which is sufficiently resilient andelastic under the pressure used to inflate the balloon 16. The balloon16 itself may also be made of polyethylene, and may be a thickpolyethylene which is nonelastomeric under range of pressure used toinflate the balloon 16. When the balloon 16 and balloon cover 27 aremade of the same material or a miscible material, the balloon 16 may beheat sealed to the balloon cover 27 at various points to prevent theballoon cover 27 from inadvertently slipping off the balloon 16. Whenthe balloon 16 and balloon cover 27 are made of different or immisciblematerials, they may be attached with adhesive or through the use ofother suitable fasteners.

In the preferred embodiment of a method of using the devices disclosedherein, the surgeon uses a balloon loaded dissector to create a workingspace under the skin and over the saphenous vein suitable forlaparoscopic techniques. The surgeon makes one or more incisions asshown in FIG. 3, to expose the saphenous vein. These incisions arereferred to as cut-downs. An incision at the knee 12, an incision at thegroin 13, or an incision close to the ankle 14 can be used. In FIG. 3,the saphenous vein 6 can be seen through the cut-downs 12, 13, and 14.It will be apparent from the description that the use of three or fourincisions to harvest the entire saphenous vein is merely a matter ofconvenience, and those particularly skilled in laparoscopic proceduresmay require fewer incisions, and smaller incisions than illustrated maybe required.

After insertion, the balloon loaded blunt dissector 15 is pushed alongthe blood vessel until the balloon tube 16 is located over the desiredlength of the saphenous vein. When the balloon 16 is properly in placeit occupies a narrow tunnel over the saphenous vein. When in place, theballoon 16 is inflated through inflation tube 28. As shown in FIG. 5,the outer walls expand under inflation and the balloon cover 27stretches as the balloon 16 is inflated. The expansion of the balloon 16enlarges the tunnel. The outer diameter of the balloon tube 16 definesthe size of the tunnel that is created, and the outer diameter may becontrolled during manufacture and during inflation. Also as shown inFIG. 5, the guide rod 20 may be conveniently replaced with an endoscope29 which can also serve as the pushing member. The endoscope 29 can bechosen to have an outer diameter matching the support tube, or it can beprovided with a stop collar 30, both constructions serving to couple theendoscope 29 to the balloon tube 16 so that pushing on the endoscope 29serves to push the balloon 16 into the body.

When the balloon 16 is deflated through the inflation tube 28, theballoon cover 27 serves to compress and collapse the balloon 16 andsqueeze the inflation fluid out of the balloon 16, thus returning theballoon 16 to the collapsed state shown in FIG. 4. After the balloon 16has been collapsed by the elastic force of the balloon cover 27, thedevice 15 may be further advanced or pulled-back from its position inthe body, and repositioned at another area of interest. When the balloon16 is repositioned, it may be re-inflated to enlarge the tunnel. Theballoon may be repeatedly inflated and deflated in this manner.Alternatively, the balloon cover 27 may be removed by pulling itproximally out of the incision to allow the balloon 16 to expand.

FIG. 6 shows an alternate embodiment of a balloon loaded bluntdissector. The guide rod 31 is provided with a slender metal rod 32fitted with an enlarged tip or olive tip 33. The guide rod 31 may bereplaced by a scope if visualization is desked. The balloon 34 is a longslender cylindrical balloon, with or without a central lumen. A guidetube 35 is attached to the outside of the balloon 34 and the guide rod31 fits through the guide tube 35. The balloon 34 is uninflated in FIG.6, and the balloon 34 and guide tube 35 are shown inside the ballooncover 27. The balloon 34 of FIG. 6 is used in the same way as theballoon 16 of FIGS. 4 and 5.

In operation, the apparatus is slipped over an endoscope (if utilized)or guide rod 31 and the balloon cover 27 is slipped over the apparatus.It is expected that use of an endoscope will be preferred because itallows for visualization of the anatomy at its distal tip as theapparatus pushes through the fat layer overlying the saphenous vein. Theapparatus is inserted either directly into the incision or is introducedthrough a cannula. After the guide rod 31 and balloon 34 are in placeover the blood vessel, the balloon cover 27 can be pulled out of theincision, and may be provided with a weakened section to facilitateremoval. The balloon cover 27 may be pulled back gradually as theballoon 34 is inserted to uncover that portion of the balloon 34 whichis inside the body, and the balloon 34 can be inflated to dissect alarger tunnel in the early stages of insertion. The balloon cover 27 mayalso be left in place and, if made of a resilient material, can be usedto compress the balloon 34 after deflation to facilitate repositioningof the assembly. After full insertion, in a preferred method of use, theballoon 34 may be left in place in the tunnel while the endoscope isutilized to view the interior surfaces of the body at the tip of theapparatus, as shown in FIG. 3a. If the balloon 34 is provided with acentral lumen, endoscopic instruments may be passed through said centrallumen to perform surgical procedures on body parts such as the saphenousvein and communicating veins of the leg. In situations where it isdesirable to insufflate the tunnel created by the balloon 34, theballoon 34 may be deflated and pulled out of the tunnel through cut-down13, and a cannula port 36 with insufflation tube 37 may be inserted intothe same cut-down as shown in FIG. 3b. A secondary endoscopic accessport 38 may be inserted into the knee incision 12 to pass a variety ofinstruments into the work space.

The step of removing the balloon cover 27 may be avoided if the ballooncover 27 is perforated along a number of longitudinal lines and sealedto the balloon 34 along interstitial longitudinal lines, so thatexpansion of the balloon 34 tears the balloon cover 27 to allowexpansion, but the pieces stay fixed to the balloon 34 so that they maybe removed easily.

The balloon dissectors disclosed herein can be used in other proceduresbesides dissection for vein harvesting, and its description in thatenvironment is merely intended to be illustrative of the device. It isreadily apparent that the devices and methods may be used for tunnelingand enlarging working spaces over other long organs of the body. Variousarteries and veins must be exposed and mobilized for other operations,such as popliteal bypass, or a dialysis vein loop. In these operations,a vein must be harvested, and the sites at which the vein will beattached or anastomosed must also be uncovered. The balloon dissectormay also be used to gain access to any blood vessel for any type ofvascular surgery. For example, communicating veins or perforators in thecalf may be exposed by dissecting the muscles deep within the calf toexpose these blood vessels to accomplish a Linton procedurelaparoscopically. The devices and methods may be used to expose thoseportions of the arteries to which grafts will be placed.

Other vessels may be dissected from surrounding tissue, such asfallopian tubes, spermatic cords, bile ducts, intestines and others.These vessels may be dissected and mobilized laparoscopically using thetechniques described above. The device may also be used to retrofit anyscope with a balloon dissector to dissect along a tunnel under directvision. The balloon can be used to guide or support any scope within anexisting space that needs periodic dilation to permit advancement of thescope. For example, a colonoscope may be fitted with the balloondissector and used to facilitate insertion of the colonoscope into thecolon, especially around the splenic flexure, by inflating the balloonwhen the tip of the colonoscope approaches the splenic flexure. Aurethral scope may be fitted with the balloon dissector to facilitateinsertion of the scope into the urethra, which often requires dilationbefore insertion of a scope. The balloon dissector may be used incombination with any scope as an anchor, which while inflated serves tohold a scope in place within the body. While the preferred embodimentsof the devices and methods have been described, they are merelyillustrative of the principles of the invention. Other embodiments andconfigurations may be devised without departing from the spirit of theinventions and the scope of the appended claims.

I claim:
 1. A method of dissecting layers of tissue to create a workingspace between the tissue layers, said method comprising:providing anelongate balloon tube and a substantially rigid pushing member disposedwithin the balloon tube, the pushing member being coupled to the balloontube; inserting the balloon tube between the layers of tissue; pushingthe balloon tube by pushing the pushing member along a path to bedissected between the layers of tissues; and inflating the balloon tubebefore the balloon tube is inserted between the tissue layers to causethe balloon tube to expand and create the working space between thelayers of tissue.
 2. A method of dissecting layers of tissue to create aworking space between the tissue layers, said methodcomprising:providing an elongate balloon tube and a substantially rigidpushing member disposed within the balloon tube, the pushing memberbeing coupled to the balloon tube; providing a balloon cover surroundingthe balloon tube; inserting the balloon tube between the layers oftissue; pushing the balloon tube by pushing the pushing member along apath to be dissected between the layers of tissue; removing the ballooncover from the balloon tube after the balloon tube has been pushedbetween the tissue layers along the path to be dissected; and inflatingthe balloon tube to cause the balloon tube to expand and create theworking space between the layers of tissue.
 3. A method of dissectinglayers of tissue to create a working space between the tissue layers,said method comprising:providing an elongate balloon tube and asubstantially rigid pushing member disposed within the balloon tube, thepushing member being coupled to the balloon tube; inserting the balloontube between the layers of tissue; pushing the balloon tube by pushingthe pushing member along a path to be dissected between the layers oftissue; inserting an endoscope into a central lumen in the balloon tubeand viewing the path between the tissue layers through the endoscope asthe balloon tube is pushed between the tissue layers along the path tobe dissected; and inflating the balloon tube to cause the balloon tubeto expand and create the working space between the layers of tissue. 4.A method of dissecting layers of tissue to create a working spacebetween the tissue layers, said method comprising:providing an elongateballoon tube and a substantially rigid pushing member disposed withinthe balloon tube, the pushing member being coupled to the balloon tube;inserting the balloon tube between the layers of tissue; pushing theballoon tube by pushing the pushing member alongside the saphenous veinin the leg; and inflating the balloon tube to cause the balloon tube toexpand to dissect the saphenous vein free from connective tissues.
 5. Amethod of dissecting layers of tissue to create a working space betweenthe tissue layers, said method comprising:providing an elongate balloontube and a substantially rigid pushing member disposed within theballoon tube, the pushing member being coupled to the balloon tube;inserting the balloon tube between the layers of tissue; pushing theballoon tube by pushing the pushing member along a path to be dissectedbetween the layers of tissue; inflating the balloon tube to cause theballoon tube to expand and create the working space; deflating theballoon tube; repositioning the balloon tube by moving the balloon tubebetween the tissue layers along the path to be dissected to a pointremote from the point where the balloon tube was first inflated; andinflating the balloon tube again to selectively enlarge the workingspace between the layers of tissue.